A carbody of a railcar is supported by a bogie through a carbody suspension including a bolster spring. The bolster spring is a spring provided between a bogie frame of the bogie and the carbody. The bolster spring eases impacts applied from the bogie to the carbody to improve a ride quality of the railcar. As the bolster spring, an air spring is typically used. The air spring can expand and contract in an upward/downward direction by the supply or discharge of compressed air to or from an air chamber formed inside the air spring. By utilizing the expansion and contraction of the air spring, an automatic level controlling operation, a carbody inclination controlling operation, and the like are performed in the railcar. The automatic level controlling operation is an operation of maintaining the height of the railcar within a certain range. The carbody inclination controlling operation is an operation of inclining the carbody such that excessive centrifugal force acting on passengers when the railcar travels through a curved line is reduced.
The air spring includes a height stopper for the purpose of preventing the spring height of the air spring from becoming too high beyond a predetermined allowable range. Known as the height stopper of the air spring is a so-called mechanical stopper configured to mechanically restrict upward displacement of the carbody relative to the bogie by contact between a first restricting member provided at the bogie and a second restricting member provided at the carbody. In addition to the mechanical stopper, the following height stoppers of the air spring have been proposed.
For example, in the railcar described in PTL 1, the air spring is provided with an emergency exhaust valve configured to open when the spring height of the air spring exceeds the allowable range. When the spring height of the air spring falls within the allowable range, an open/close portion of the emergency exhaust valve is coupled to the carbody by a stretchable link. When the spring height exceeds an allowable upper limit, an upward movement of the carbody is transmitted to the open/close portion of the emergency exhaust valve through the link. Thus, the emergency exhaust valve opens.
Further, for example, in the railcar described in PTL 2, the air spring is provided with an exhaust bypass, and the exhaust bypass is provided with a mechanical valve configured to open when the spring height of the air spring exceeds the allowable range. The air spring includes an operation arm of the mechanical valve in the air chamber. The operation arm is operated by a diaphragm when the air spring becomes an excessive air supply state. Thus, the mechanical valve opens.